There are better MMORPG's out there than FF11; if you're going to pay for a game monthly, might as well pay for the best one there is or at least one of the best - FF11 is neither of which.
If you drool over anything with a Final Fantasy label slapped onto it you might like 11, but otherwise, go for WoW, or if you like Sci-Fi stuff, go for EVE Online. Alternative to those are some of the newer ones like Conan, which might be worth a shot; the only issue with WoW or EVE would be that they are older games so you would be behind. The system of "leveling" in EVE is such that you can NEVER catch up to players who have been playing longer than you; you train in real time online or offline.
With WoW you can catch up by getting into good guilds and then guidldhopping your way to the top of your battlegroup, however there is so much to do that you have already missed out on (nobody raids MC, BWL, ZG, AQ40, AQ20, Naxx anymore and those were ungoodly fun) so you'd need to learn fast when it comes to raiding, and settle for a guild that isn't top notch until you have good enough gear and experiance for the better ones. However, there is a new expansion coming soon, so it might be a great opportunity to get into it, the last expansion was quite massive and this new one will be too; but i'd get the game BEFORE it comes out so you can get adjusted and used to it and won't be 100% new once its there.
There are also a lot of Free MMO's out there, but none of them are as good as the paying games thusfar, i've tried a ton of them